IGIDR- SAMPLE PAPER

[jack]

Q.1- The mean wage and s.d of 150 men were Rs. 60 and 4 per week respectively and that of another 200 men were Rs 90 and 3 per week. The s.d of the work force of 350 men considered as one group is
1) 9
2) 32/7
3) 15.5
4) 21.1
5) none of these

Q.2- the values of K for which the system of equations
X+Y=4
KX+2Y+3z=1
2x+Y+KZ=5
Does not have any solution, are
1) 1,3
2) -3,-1
3) 3,-1
4) 1,-3
5) none of these

[rongmon]

for combined standard deviation, see

http://www.emathzone.com/tutorials/basic-statistics/combined-variance.html

[Dreyfus]

For q2...no solution implies that the set of equations are inconsistent nd for dat by Cramer's rule the determinant of coefficient matrix should b 0....

[C10]

FOR Q2, set the determinant of the coefficients to zero and solve